Laser Speckle Contrast Imaging of the Blood Perfusion in Glabellar Flaps Used to Repair Medial Canthal Defects

Laser speckle contrast imaging of perfusion in oncological clinical applications: a literature review

BACKGROUND

Laser speckle coherence imaging (LSCI) is an emerging imaging modality that enables noninvasive visualization and assessment of tissue perfusion and microcirculation. In this article, we evaluated LSCI in imaging perfusion in clinical oncology through a systematic review of the literature.

METHODS

The inclusion criterion for the literature search in PubMed, Web of Science and Scopus electronic databases was the use of LSCI in clinical oncology, meaning that all animal, phantom, ex vivo, experimental, research and development, and purely methodological studies were excluded.

RESULTS

Thirty-six articles met the inclusion criteria. The anatomic locations of the neoplasms in the selected articles were brain (5 articles), breasts (2 articles), endocrine glands (4 articles), skin (12 articles), and the gastrointestinal tract (13 articles).

CONCLUSIONS

While LSCI is emerging as an appealing imaging modality, it is crucial for more clinical sites to initiate clinical trials. A lack of standardized protocols and interpretation guidelines are posing the most significant challenge.

The effect of traction force on eyelid blood perfusion during closure of defects

PURPOSE

In oculoplastic surgery the eyelid tissue is frequently stretched in order to repair defects after tumor surgery. However, there is a paucity of research regarding how stretching affects eyelids. The purpose of this study was to gain insight into how traction force affects eyelid stretch as well as tissue perfusion, using a laser-based in vivo monitoring technique.

METHOD

Lower-lid pentagonal resections were performed in eight patients and a total of nine eyelids. The medial section of the eyelid was then stretched using a dynamometer up to a force of 2.3 Newtons (N), and eyelid stretching and blood perfusion were continuously measured using laser speckle contrast imaging.

RESULTS

Tissue perfusion decreased exponentially when eyelid tissue was stretched, with an initial sharp decline followed by a more gradual reduction. Perfusion approached zero at a force of approximately 2.0 N. The length of the eyelid increased with increasing force up to 1.5 N, after which there was only a very slight increase in length.

CONCLUSIONS

Eyelid tissue seems to respond to traction in a non-linear fashion, where the initial force results in the greatest eyelid stretching and reduction in blood perfusion. The results provide information on the effects of a large force for direct closure of large eyelid defects. Considering how quickly perfusion approaches zero, the high success rate of eyelid reconstruction surgery is likely a testament to the extensive vascularization of the periocular region.

Forehead flap perfusion monitored by laser speckle contrast imaging: Importance of flap length and thickness

Purpose

Forehead flaps are commonly used in oculoplastic surgery to cover defects after tumor excision. Blood perfusion is vital for flap survival. The aim of this study was to monitor the perfusion in forehead flaps and investigate the impact of flap length and thickness.

Methods

Nineteen forehead flaps in patients undergoing direct brow lift were studied. Perfusion was monitored using laser speckle contrast imaging, immediately after raising flaps consisting of epidermis, dermis, and subcutaneous tissue, and after removing the subcutaneous tissue resulting in a thin flap.

Results

Perfusion decreased gradually along the length, the mean value being 44% at 5 mm and 26% at 15 mm from the base, in thick flaps. Perfusion was significantly lower in thin flaps, being 13% when measured 15 mm from the flap base (p < 0.0024). Perfusion was better preserved in thick than in thin flaps. Very low perfusion was observed 16.7 mm (16.0-17.3 mm) from the base in thick flaps, and from 10.2 mm (9.8-10.6 mm) from the base in thin flaps (p < 0.0001).

Conclusions

Flap thickness is important in maintaining adequate blood perfusion and thus increasing the probability of flap survival. This may be particularly important in long flaps and in patients with impaired microcirculation.

Projection mapping system for laser speckle contrast image: feasibility study for clinical application

Significance

Laser speckle contrast images (LSCIs) have been utilized to monitor blood flow perfusion. However, they have conventionally been observed on monitor screens, resulting in potential spatial mismatching between the imaging region of interest (IROI) and monitor screen.

Aim

This study proposes a projection mapping (PM) system for LSCIs (PMS_LSCI) that projects LSCIs to directly observe the blood flow perfusion in the IROI.

Approach

The PMS_LSCI consists of a camera, imaging optics, a laser projector, and graphic user interface software. The spatial matching in the regions of interest was performed by adjusting the software screen of the LSCI in the IROI and evaluated by conducting in-vitro and in-vivo studies. An additional in-vivo study was performed to investigate the feasibility of real-time PM of the LSCI.

Results

The spatial mismatching in the regions of interest was ranged from 2.74% to 6.47% depending on the surface curvature. The PMS_LSCI could enable real-time PM of LSCI at four different blood flow states depending on blood pressure.

Conclusions

The PMS_LSCI projects the LSCI in the IROI by interacting with a projector instead of the monitor screen. The PMS_LSCI presented clinical feasibility in the in-vitro and in-vivo studies.